It is well known in the farm equipment industry to meter seeds or other particulate materials from bulk supply hoppers on the seeder into one or more airstreams that transport the seeds to a corresponding number of distribution towers, where each primary stream of air and seeds is divided into a number of secondary streams. The secondary streams are then directed to openers on the machine that deposit the seeds into the ground as the seeder advances.
It is also well known to temporarily shut off one or more of the hoses that carry the secondary streams so that the corresponding opener does not deposit any seeds, thereby creating a plant-free row in the field sometimes known as a tram line. Valves and electrically energized valve actuators of various types have been employed to carry out this function. In addition, electronic sensors have typically been provided on the secondary hoses to detect whether seeds are in fact passing through the hoses as anticipated. However, seeders necessarily operate in relatively harsh environments, and in the past the sensitive valves, actuators and sensors have been subject to malfunction and premature wear due to excessive exposure to such hostile conditions.
As the primary stream of air and seeds enters the distribution head of the tower through an inlet in the bottom of the head, the seeds are subjected to an abrupt right angle change in direction as they are split into secondary streams and exit the head horizontally. In prior towers, a significant amount of turbulence has been created at this location that can adversely affect the output rate of the tower and may damage the seeds.
Accordingly, the present invention provides a seed distribution tower wherein sensitive devices such as tram line valves, actuators and/or sensors are protectively housed within the interior of the distribution head of the tower, away from harsh environmental elements that could damage or ruin the devices. In another aspect of the present invention, the distribution head of a seed distribution tower is provided with an internal plenum configured to reduce turbulence and promote more laminar flow as the primary stream splits into secondary streams and transitions from vertical to horizontal movement, thereby increasing the flow rate through the tower and reducing seed damage. An eased inlet into the bottom of the plenum from the conduit eliminates the squared off corner of prior designs to assist the incoming air and seeds in making a smooth transition. In one embodiment, the eased inlet comprises an opening in the floor of the plenum and a raised rim around such opening, preferably arcuate in transverse cross-section, An inverted overhead cone projects down from the top wall of the plenum in concentric relationship with the inlet to cooperate in transitioning and splitting primary stream. Other embodiments include a beveled opening into the plenum having either substantially flat or rounded sloping sidewalls.